This invention relates to a disc check valve construction for a fluid delivery system useful for dispensing precise volumes of fluid.
Prior to the present invention, fluid delivery systems have been available which minimize system volume and which minimize intermixing of fluids while delivering a precise amount of a fluid for use such as in a chemical reaction. These systems generally are utilized for chemical processes such as diagnosis or analytical apparatus or for processes that involve a large number of sequentially effected chemical reactions such as in protein synthesis, deoxyribonucleic acid (DNA) synthesis or when sequencing proteins.
Check valves that permit fluid flow in only one direction are commonly utilized in fluid delivery systems to effect delivery of discrete fluid volumes sequentially from a fluid reservoir to a point of use. When utilizing such fluid delivery systems, it is desirable to minimize conditions, which may result in variation in volume of the discrete fluid samples being delivered. In order to minimize such volume variations, it is desirable that the check valve have a quick response to changes in pressure, a large hydraulic force applied to the movable portion of the check valve such as a ball, and that the movable portion does not chatter or slam when moved. In addition, it is desirable that the check valve have a low internal volume for high performance fluid delivery systems.
Accordingly, it would be desirable to provide a check valve and a fluid delivery system which utilizes a check valve construction which reduces back pressure within the valve thereby reducing the pressure needed to move the movable portion of the valve and to provide a quick response time for opening or closing the valve.